DESCRIPTION

Often there are several possible providers of some functionality your program needs, but you don't know which is available at the run site. For example, one of the modules may be implemented with XS, or not in the core Perl distribution and thus not necessarily installed.

Best attempts to load modules from a list, stopping at the first successful load and failing only if no alternative was found.

FUNCTIONS

Most of the functionality Best provides is on the use line; there is only one callable functions as such (see which below)

If the arguments are either a simple list or a reference to a simple list, the elements are taken to be module names and are loaded in order with their default import function called. Any exported symbols are installed in the caller package.

use Best qw/A Simple List/;
use Best [ qw/A Simple List/ ];

IMPORT LISTS

If the arguments are a listref with a listref as its first element, this interior list is treated as the specification of modules to attempt loading, in order; the rest of the arguments are treated as options to pass on to the loaded module's import function.

To specify a null import (use Some::Module ()), pass a zero-element listref as the argument list. In the pathological case where you really want to load a module and pass it [] as an argument, specify [ [] ] as the argument list to Best.

PRE-VALIDATION

You may prevent Best from attempting to load a module by providing a function as a parameter to if. The module will only be loaded if your function returns a true value.

POST-VALIDATION

use Best Module => { ok => CODEREF };

You may prevent Best from settling on a successfully loaded module by providing a function as a parameter to ok. Best will follow all of its normal rules to attempt to load your module but can be told to continue retrying if your function returns false.

ARBITRARY CODE

A code reference may be substituted for module names. It will be called instead of attempting to load a module. You may do anything you wish in this code. It will be skipped if your code throws an exception or returns false.

In some cases--for example, class methods in OO modules--you want to know which module Best has successfully loaded. Call Best->which with the first in your list of module alternatives; the return value is a string containing the name of the loaded module.

DEPLOYMENT ISSUES

If you want to use Best because you aren't sure your target machine has some modules installed, you may wonder what might warrant the assumption that Best.pm would be available, since it isn't a core module itself.

One solution is to use Inline::Module to inline Best.pm in your source code. If you don't know this module, check it out -- after you learn what it does, you may decide you don't need Best at all! (If your fallback list includes XS modules, though, you may need to stick with us.)

Best.pm is pure Perl and a single module with a convenient license, so you can also just drop it in your project's lib directory.

SEE ALSO

AUTHORS

Joshua ben Jore, <jjore at cpan.org> has made some significant contributions.

DIAGNOSTICS

What modules shall I load?

Best wasn't given a list of modules to load.

No viable module found: %s

None of the module alternatives loaded.

Something's wrong!

An assertion failed. This means that either there is a bug in the data you fed to Best or a bug in Best.

The code is scattered with assertions and debugging output that can be enabled by putting a true value in the environment variables TRACE_BEST and DEBUG_BEST.

Enabling TRACE_BEST also enables the debugging code.

BUGS

Please report any bugs or feature requests to bug-template-patch at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Best. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SUPPORT

You can find documentation for this module with the perldoc command.

perldoc Best

You can also contact the maintainer at the address above or look for information at:

COPYRIGHT (The "MIT (X11)" License)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Module Install Instructions

To install Best, simply copy and paste either of the commands in to your terminal